Bioefficacy of Insecticides against Tur Pod Bug, Clavigralla gibbosa (Spinola) on Pigeonpea [Cajanus cajan (L.) Millsp.]

Pod sucking bugs are the key impediments for the low productivity in India. Nymphs and adults of tur pod bug, Clavigralla gibbosa (Spinola) suck the cell sap from the pods and cause loss of the grain. Because of its high fecundity and wide host adaptability, it is necessary to check its damage potential. For this purpose, an experiment on bioefficacy of insecticides against this insect was conducted in the laboratory-cum-field conditions on cultivar “Paras” during kharif season 2010–11, 2011–12 and 2012–13. Eight insecticides viz., endosulfan 35EC, monocrotophos 36SL, chlorpyriphos 20EC, quinalphos 25EC, triazophos 40EC, decamethrin 2.8EC, fenvalerate 20EC and cypermethrin 25EC were selected based on their LC₅₀ values against this insect. Among the tested insecticides, cypermethrin proved most toxic (63.94 times) against adults of C.gibbosa followed by decamethrin. Quick knock down effect of decamethrin and fenvalerate was recorded in the field conditions. Therefore, the combinations of decamethrin and quinalphos with DDVP (76 EC) were also tested under field conditions. Cypermethrin, decamethrin plus DDVP, decamethrin and monocrotophos were found effective in managing the C.gibbosa population upto 10 days after application. None of the insecticides could manage the bug population below ETL after 14 days of their application. Application of cypermethrin @ 188 mL ha⁻¹ recorded the highest grain yield, highest net monetary returns and highest incremental cost benefit ratio, followed by decamethrin, fenvalerate and monocrotophos. Either of dimethoate or oxydemeton methyl could also manage the bug population.